Electrical musical instrument



N. LANGER ELECTRICAL MUSICAL INSTRUMENT Filed April 5'. 3955 s sheets-sheet z Em S... NL. ...P

INVENTOR Y M'colas [anger SIRNEY March 24, 1936. i N, LANGER 2,035,238

` y ELECTRICAL MUSICAL INSTRUMENT Filed April 5, 1953 5 Sheets-Sheetv 3 INJENTOR BY Mchn/s langer TORNEY Patented Mar. 24, 1936 UNI-TED STATES PATENT OFFICE 2,035,238 ELEcTmcAL Musical.l INSTRUMENT Nicholas Langer, Deep River-, Conn., assignor of sixty-six and two-thirds per cent to John Halmagyi, Budapest, Hungary Application April 5, 1933, SerialNo. 664,486

l10 Claims. (Cl. 84-1) The present invention relates to electrical musicalinstruments containing glow-discharge lamps and more particularly to electrical musical instruments of the type using glowdis` charge lamp circuits .to produce electric oscilla tions of'diiferent frequencies capable of being transformed into musical sounds of different pitch.

It is an object of the present invention to provide an electrical musical instrument; having a better control of the frequency and of the wave form of the electrical oscillations produced by the charging and discharging of condensers through resistances and glow-discharge lamps.

It isv a further object of the invention to provide an electrical musical instrument capable of extending the pitch range thereof by collectively changing the frequencies of a plurality of musical notes while at the same time maintaining their relative frequencies or intervals unchanged.

It is another object of the invention to provide an improved method for producing small periodic changesin the pitch of the musical notes, called thetremolo effect, and to use the same means for obtaining a good imitation of the sound quality characteristic to the tone of a mandolin or banjo or generally to that of the plucked string. It is also .within the contemplation of the present invention to provide an improved and simple circuit fr producing a multiplicity of electrical oscillations of different frequencies capable of individual'adjustment.

Other and further objects ofthe invention will become apparent from the following specication taken in conjunction with the. accompanying drawings in which v4:0 Fig. l is a diagrammatic view of a glow-discharge lamp oscillator containing a variable series impedance in the main circuit embodying the principles of the present invention;

Fig. 2 shows a schematic view of a circuit of an electrical musical instrument of the glowdischarge lamp type embodying the present invention in which the absolute pitch of every noteV can be changed simultaneously while at the same time changes in the relative pitches (intervals) are compensated for;

Fig. 3 depicts diagrammatically an improved embodiment of a circuit for producing the socalled tremolo and banjo-effects in an electric musical instrument; and Figs. 4 and 5 illustrate a schematic view of a circuit of the improved electric musical instrument using variable condensers for the individuail adjustment of a vplurality of musical notes. l

. Broadly stated all of 'these circuits illustrated and described herein show the fundamental parts which are absolutelynecessary ign-order to obtain the 'desired effects. Of course, as those skilled in the art will readily understand, a. great number of refinements canbe applied to each circuit. Most of the electrical elements as capacities, resistances, inductances, and the like can be made variablein steps or continuously as desired. Thermionic amplifiers' or transformers can be used between the oscillation generator and the sound-producing means and the output can be taken oi in many Ways other than connecting the sound-producing means directly in series with the main circuit. Means for changing the amplitude and the harmonic content of the oscillations produced can be provided by potentiometers, filter circuits, etc. in accordance with the lconventional practice of the electrical art. Although most of the circuits described are capable of producing one musical note at a time, it is evidentthat a plurality of musical notes or chords can be produced by arranging a plurality of circuits of similar kind, that .certain parts of the circuits such as the source of current and the soundproducing means, may be common to all the circuits.

Referring more particularly to Fig. 1 an arrangement of a glow-discharge lamp oscillator is illustrated. 'I'he reference character B designates a current source which is in a circuit containing a glow-discharge lamp G, a resistance R, a condenser C and a sound-producing means L. In the circuit a variable impedance I is connected in series which is preferably an ohmic resistance. By incorporating a variable impedance in the circuit novel and unexpected results of great practical importance can be obtained.

From a theoretical point of view, the fretrary' to expectations and theory, it has been found that if the impedance is increased from zero up to a final value, the frequency will increase with increasing impedance instead o! decreasing. As yet, no explanation can be offered for the strange behavior of this circuit but the phenomenon can be easily demonstrated experimentally. It has been Aalso discovered that there must be a certain numerical relation between the value of the capacity of the condenser, of the resistance, of the impedance and of the voltage of the current source B in order to cause the desired effect. For instance, to give a practical example, if the capacity equals -0.001 microfarad, R the resistance equals 1 megohm, the voltage of B 'about 110 volts, then the impedance can be varied from zero to about 500,000 ohms and the frequency will increase with it, but after pmsing this critical impedance the glow-discharge lamp will be continuously lighted and will stop oscillating.l

In Figs.-2 and 3 circuitsare depicted which illustrate practical embodiments of the foregoing principle.

Referring more particularly to Fig.. 2 a cir- -cuit of an electric musical Ainstrument capable ofproducing numerous musical notes of different pitch is shown.. Referencecharacter B designates the current source,- T the output transformer :with associated sound-producing means, G is the glow-discharge lamp, C,-I a condenser, I a variable impedance, R-I to R-n are fixed resistors in series any number of which can be connected across C-I by operating one of the switching keys K- to K-n and closing one of the contacts Q-l to Q-n. Means for controlling the volume, tone color of the sounds produced or adjusting the electromotive force; amplifiers and the like auxiliary apparatus have been omitted for 'the sake of simplicity.

In the practical manufacture of an electrical musical instrument, resistors R-l to R-n are selected so as to give a diiIerent note of the tempered scale for every successive key, K-l .to K--n. Since resistors R-l to R-n vary between 40,000 and 1,000,000 ohms, no variable resistors of this kind which are inexpensive and constant enough can be obtained on the market.

Consequently, it is necessary to have in 4stock a large quantity of fixed resistors of every intermediary value between said extremes and to select the adequate resistors by a long and tiresome method of trial and error. Although the tuning of an instrument of this kind is remarkably constant,'slight variations of the characteristics of the glow-discharge lamp (depending especially on the break-down and extinction voltages) might change the intervals between the individual notes. This can now be easily compensated for all the intervals by the variable impedance I. The effect of increasing the impedance is to make all the intervals closer and vice versa. Thus, the instrument can be tuned for about'the mddleposition of impedance I,

. that is resistors Rf-l to Rn are selected so as to give n successive notes of the tempered scale, when keys K-I' to K- n are actuated. Suppose now'that by a change in the characteristics of -the glow-discharge lamp the intervals become closer or wider than necessary, they can be easily brought back by adjusting a single control of the impedance. In this manner a tiresome and expensive retuning of the instrument (i. e. changing of all the resistors) is I when in eliminated. A wire-wound or a carbon com- In Fig. 2, another vpossible use ofthe series impedance is also depicted. I f aA condenser C-2 of approximately the same capacity is connected across C-I, then every note produced by the instrument will sound an octave lower, because the capacity in the circuit is doubled. M usically speaking, the rang'e of the instrument has been transposed an octave lower; lOf course, by giving suitable values to the condenser 0 2', it is possible to transpose the range by any amount, in steps or continuously in case condenser'C-Z is continuously variable.

Thetransposing larrangement is of great practical importance because it extends the range of the instrument considerably'. The diiiiculty .of' this simple process lies in the circumstance that by connecting condenser C-LZ across condenser C-I not every note will be lowered to exactly .the same amount, the intervals will be made a little smaller or closer, suflciently so -as to be disagreeable to the musically trained ear. This -ca'n now be easily compensated 'for by reducing the series impedance' which has. the contrary effect of `making the intervals wider.

Thus, by arranging a double-pole switch S-l and S--Z which when connectingcondensers' .C-2 across condenser C-l atthe same time In Fig. `3 an embodiment of this circuit arrangement is depicted. Batteries B, glow lamp G, condenser C, .resistors R-I to IiP-n, keys ranged in exactly the same way as in Fig. 2 and their connections do not require anyfurther ex'- planation.v Reference character A designates a control lever `pivotedat pivot E which can be moveda little to the right and to the left and which is capable of closing one of the contacts D=I orD-2. Switch S is capable of connecting contact D-2 to one end of the impedance the lower position, vor connecting contact D-I to-contact D-Z when in the higher position. First the case when switch S is closing contact D-4 as indicated in Fig. 3 is considered. Suppose that control lever A is inthe intermediary position not touching contacts D- I or D2, the main circuit, which is-broken between the negative pole of the. battery and the output transformer T-|, is completed through switch S, contact D-4 and through the impedance I. By moving contact lever A tc the right and to the left impedance I will be short-circuited `every time control lever A touches contact D-2, thus causing a small dro; of pitch repeating periodically, (i. e. the desirec tremolo eiect). If switch S -is put .in the uppei position, contacts D-i and D-3 will be connected to each other and the negative pole of the battery, while control lever A, as always,

is connected to the upper end of the primary' winding of the output transformer -T-I. Thusthe main circuit is completely interrupted unless control lever A is moved to the right and to the left and intermittently closes contacts D-.i or D-2. This means that operating one of the keys K-I to K-n alone is not suflicient to produce the note because it is necessary to lalso operate the control lever A simultaneously.

the plane of the drawing, the operator can utilize this motion preferably for varying the volume.

The value of impedance I is not at all critical, but depends slightly on the total impedancein the circuit. A resistance of about 1500 to about 3000 ohms is satisfactory in most cases.

From the preceding consideration, the importance of the influence of series impedances on the tuning of electrical musical instruments becomes apparent. Evidently even the primary of the output transformer, usually arranged in the main circuit, has a certain impedance, which is also varying for instance due to .direct current magnetization of the iron core or due to the reflection of the loadl on the secondary winding back to the primary. Of course, these variations of impedance in the main circuit are undesirable. A simple-method to reduce them to a negligible amount .is to. connect another transformer T-2 after T-I, so that secondary Sc-I of T-I is connected through the volume control potentiometer V to. the primary Pr-l of T-2 and only the secondary Se-2 of transformer T2 is connectedto the thermionic amplier M and soimd producing means L. The impedances of Se-l and Pr-Z are preferably matched with each other and with that of volume control V, and the Winding ratio of transformers T--I and T-Z is chosen so as to give a4 combined turn ratio advantageous forthe amplification.

The manifold and important advantages of this arrangement are obvious. The coupling between the main circuit of the glow-discharge lamp oscillator and the amplifier becomes extremely loose. Feed-backs, changes of impedance in the main circuit. direct 'currentmagnetization of the transformer core are eliminated. The volume control is dealing with a a pure A. C. current without any D. C. component, s o that the load on it is considerably -reduced thus eliminating scratches, cracking noises etc. in the sound-producing means when adjusting the volume of the sound.

Electrical musical instruments of the present type which are capable of producing numerous musical notes of dierent respective pitch'es and which essentially consist of a glow-discharge lamp, a condenser, a current source and a soundproducing means in series with said glow-discharge lamp, a plurality ofv resistors in series 4capable' of being shunted .partly 4or totally across the condenser, function as satisfactorily from the electrical point of view as-from the musical point of view. The vinstruments can be built at little cost, only take up small space vpublic utility.

e 3 and can be operated fora long time without any replacements whatever.

Since the frequency of 'the Aglow-discharge lamp oscillator varies not only with the resistance in circuit, but with the capacity and electro-motive force as well, electrical musical instruments` of the glow-discharge lamp type can be built in which a plurality of musicalI notes. of different respective .pitches are pro- .duced by varying the electro-motive force or.

the capacity in the circuit.

Instruments in which ,the different musical notes are obtained by different voltages tapped off on one or on a plurality of current sources or potentiometers have been already described,

and apart from the slight inconvenience of the relatively higher voltages involved. are practicable especially when the operating current is obtained from the electric supply lines of a The capacity method of tuning, however. is much simpler and morereliable in operation, and the circuit is practically identical with that of resistance tuning which can be easily seen, for instance, from Fig. 2. It is only necessary to put two resistors of adequate value in the place of condensers C-I and C-2 and substitute a plurality of condensers for resistors Rf-i to R-n and the circuit will be capable of prof ducing musical oscillations. Now condensers have the advantage of being readily obtainable on the market in the desired capacity values and their capacity can be easily varied by com-.- pression, etc. for tuning purposes. to the foregoing condensers they are relatively small and inexpensive.

A'I'he two fundamental circuits for a glow-discharge lamp musical instrument with condenser tuning. may be `seen in Figs. 4 and 5.- In Fig. 4 aA series arrangement of condensers is illustrated whereas in Fig. 5 a parallel arrangement is depicted. Both circuits depict only one glow-discharge lamp but obviously a plurality of lamps in similar arrangements can be also used, since the circuits are equally adaptable for monophonic (solo) and polyphonic (chord) instruments. Of course, a great variety of other circuits with condensers are possible, all of which can be of advantagefor special purposes. In fact in most of the glow-discharge lamp circuits resistances and condensers can be used interchangeably without interfering with the ability of the circuit to produce electrical oscillations. The values of resistors. and condensers, of course, might have to be changed. The two circuits to be described, however, have some special advantages, which distinguish them from the great variety of possible combinations.

Referring to Fig. 4, the fundamental circuit of an electrical musical instrument is. shown but parts for controlling tone quality, volume, pitch etc. are omitted for sake of clarity. In a main circuit are the glow-discharge lamp G, current source' B, sound-producing means L and resistance R, all in series. This circuit is closed and the lamp is lighted. In an auxiliary circuit, a plurality of variable condensers C-l to C-n are arranged in series with each other In addition and switching keys K-I to K--l-n with contacts Q-I to Q-n are normally open. A switching key and contact is provided for each condenser. When -any of the switching keys is operated, a number of condensers in series up to the particular key will be shunted across the resistance R, so that the conditions for producing oscilevery switching-key operated. From the law governing the resultant capacity of condensers in series', it follows that the resultant capacity is always smaller than the capacity of any of the single condensers. In the case of two condensers in series, itis always the smaller which has more influence to the resultant capacity. A simple calculation shows that it is desired to produce successive notes of the tempered scale in the right order by operating keys K-l to IK-n of the circuit shown in Fig. 4, condenser C---Z` will be considerably larger-than condenser C-l, and condenser C-,3 vwill be smaller than condenser C--2 and condenser C--4 smaller than condenser C'-3, etc. The actual values for condensers C-I to C-n can ybe easily found by considering the fact that the frequency of oscillations is approximately in inverse ratio with the capacity and resistance in the circuit and from the condenser equation determining the resultant capacity of `two condensers in series.

Referring to Fig. V5, a parallel arrangement of variable condensers isdepicted and the rest of the circuit is identical with Fig. 4. yThe fundamental diiference between the circuits of Figs. 4 and 5 is that in the latter-the switching keys K-I to K-.n and the contacts Q--i to Q-n are normally closed, so that al1-the condensers C-l to C-n are connected in parallel and across the resistance R. Consequently, continuous oscillations are set up in the main circuit consisting of current source B, sound-producing means L, glow-discharge lamp G and resistance R. The' last condenser C-n, however, has preferably a very high capacity and is many hundred times larger than any of the preceding condensers. For instance, a capacity of 4 to l0 microfarads may be used so that the frequency of the continuous oscillation will be extremely low and will be of the order of only one oscillation in several minutes, and thus inaudible. As soo'n, however, as any of the switching-keys is depressed, one of the contacts Q--l to Q-n will be interrupted, the condensers beyond the particular key disconnected and only the condensers before the key remain in the circuit and produce an oscillation of musical frequency. For instance, if the switching-key operated is K--2, then C--3, C-4 C-n (this latter being the large silencing condenser") will be disconnected 4and only C-I plus C-2 left in the circuit.

As it will be readily seen, the fundamental difference between the circuits in Fig. 4 and Fig. 5 is that in the former in case several keys are operated simultaneously, the note corresponding to the lowest p'itch key will sound, while in the latter the note corresponding to the highest. Both possibilities have certain advantages for special purposes and embody the very important feature, that whatever keys are operated simultaneously no irrational notes will be heard, meaning by irrational a note which is falling between two successivevnotes of the tempered scale.

It is possible to combine the two circuits in Fig. 4 and Fig. 5 in one instrument with a single keyboard. An instrument of this kind comprises two glow-discharge lamps, a resistance in series with each lamp and a set of condensers in parallel respectively in series with their corresponding breaking or closing contacts associated to these resistors. Every key of the common keyboard operates two contacts independent from each other, one contact is opened and'another closed simultaneously when the key is depressed. Of course, current source and soundproducing means can be in common for both glow-discharge ,lamp circuits.

An instrumentof the present type has the advantage that it can play any two notes of its range simultaneously, since it actually consists of two independent instruments. one-of which always plays the highestandthe other alwaysthe-lowest note for any two keys depressed.

1. An electrical musical instrument 'comprising an electrical circuit containing a sourcel of current, a condenser with a shunt resistance, a glow-discharge lamp, sound -producing means capable 'of emitting sounds, and a'variable inipedance all in series, means for varying said impedance whereby the pitch of' the sound emitted 1 by said sound producing means is raised when said impedance is increased and thepitch of the said sound is lowered when the said impedance is decreased.

2. An electrical musical instrument comprising a circuit containing a source of current, a condenser with a shunt resistance, a glow-discharge lamp, a transformer having a primary in` said circuit, and an impedance, all in series..

means for short-circuitng said impedance and a sound-producing means operatively associated with the secondary of said transformer, said s ound producing means being capable of emitting a sound, the pitch of said sound being raised when the said impedance is in circuit, and the pitch of said sound being lowered when said-impedance is short-circuited. A

3. An electrical musical instrument comprising amain. electrical circuit containing a source of current, a glow-discharge lamp, a condenser,- a transformer having a primary in said circuit, and an impedance all in series; an auxiliary circuit containing a plurality of resistances in series,- a switching key for each of the said resistances located between each common point of two adjoining resistances and one side of the condenser, said key being normally open to disconnect the resistance from the main circuit and being capable of actuation for shunting a selected plurality of said resistances across said condenser thereby completing the main circuit and causing current to flow through said lamp; means for short-circuiting said impedance and sound producing means operatively associated with the secondary winding of the aforesaid transformer and capable of emitting sound, the pitch of the emitted sound being the highest when one re.- sistance is operative and the lowest when all oi the series resistances are operative and intermediate when a plurality of resistances are operative; the musical intervals between all the notes producedV being capable of simultaneow variation when said impedance in the main cir cuit is a short-circuited.

4. An electrical musical instrument comprising a main electrical circuit containing a source oi current, a glow-discharge lamp, a condenser, a transformer having its primary in said circuit, and an impedance all in series; an auxiliary circuit containing a plurality of resistances in series, a switching key for each-of the said resistances located between each common point of any two adjoining resistances and one side of thecondenser, said key being normally open to disconnect the resistance from the main circuit and being capable of actuation for shunt,- ing'a selected plurality of said resistances across said condenser and causing current to flow through said lamp; and sound producing means operatively associated with the secondary of said transformer and being capable of emitting 'sound of different pitch for every switching key operated; a second auxiliary circuit containing a condenser variable in steps and a double-pole switch capable of shunting said condenser across the main circuit condenser and simultaneously short-circuiting the main circuit impedance thereby lowering the pitch of every note the in" strument` is capable of producing by a definite amount and compensating for differences in the aforesaid change for the different notes and thereby keeping the musical intervals between the notes substantially constant by means cf the aforesaid double action.

5. An electrical musical instrument comprising an electrical circuit containing a source of current, a condenser .with a shunt resistance, a glow-discharge lamp, a sound'producing means capable of emitting-sounds, and an impedance all in series, means for short-circuiting said impedance including, an electrical contact connected across said impedancecapable of being opened and closed in rapid succession the pitch of sound emitted by said sound producing means being raised when said contact iskopened and the pitch of said sound being lowered when said contact is closed and short-circuits the said impedance.

l6. An electrical musicalinstrument comprisingy a main electrical circuit containing asource of current, a glow-discharge lamp, a condenser, a sound producing means and an impedance all in series; an auxiliary circuit containing a plurality gf resistances in series, a switching key for each of the said resistances located lbetween each common point of any two adjoining resistances and one side ofthe condenser, said key being normally open to disconnect the resist-- ance from the main circuit and being capable of actuation for shunting a plurality of said resistances across said :condenser and causing current to flow through said lamp; and an electrical contact capable of rapidly opening and closing a short circuiting lead connected across said impedance in the main circuit; said sound .producing means being capable of emitting capable of emitting sound, and an electrical conwhich varies when said contact is rapidly opened and closed and the impedance is connected across the contact, said musical sound being started and stopped when said contact is operated and the impedance is disconnected therefrom. f

8. An electrical musical instrument .comprising a. main electrical circuit containing a source of current, a glow-discharge lamp, a condenser and the primary of a transformer al1 in series; an auxiliary circuit containing a plurality of resistances in series, a switching key for each of these resistances located between each common point of two adjoining resistances and one side of the condenser, said key being normally open to disconnect the resistance from the main circuit and being capable of actuation for shunting a plurality of said resistances across said condenser and for causing current to flow through said lamp; an electrical contact inserted in said main circuit capable of rapidly opening and closing same, a switch capable of connecting an impedance across said contact and disconnecting it therefrom, and sound producing means operatively associated with said transformer and being capable of emitting sound of diiferent pitch for every switching key operated; the pitch of the emitted sound varying when said main circuit contactI breaker is operated and when the impedance connected across the same is alternatively short-circuited, the said sound starting and stopping in rapid succession when said contact -is operated and the impedance is disconnected therefrom.

9. In anelectrical musical instrument, the combination comprising a glow-discharge lamp adapted to produce electrical oscillations, a sound producing means adapted to produce sounds in accordance with said oscillations, manually operative elements for controlling the frequency of said oscillations, and a variable impedance in series with said glow-discharge lamp, the pitch of sounds produced in said sound producing means by actuation of said manually operative elements being collectively raised,

when said Aimpedance is increased and said pitches being collectively lowered when said impedance is decreased.

10. In an electrical musical instrument, the combination comprising' a glow-discharge lamp circuit adapted to produce electrical oscillations, a sound producing means associated with said circuit ladapted 'to produce musical sounds in accordance with said oscillations, manually oplerative elements for controlling the frequency of ,said oscillations and to produce musical sounds having definite intervals, a shunt condenser for collectively yvarying the pitch of said sounds by approximately the same amount, and an adjustable impedance` in series with said glow-discharge lamp forI correcting the effect of said condenser and to maintain said intervals constant. v

NICHOLAS LANGER. 

